This lecture covers the study of natural numbers, focusing on multiples, divisors, and prime numbers. It introduces the set of natural numbers, discussing properties like associativity, commutativity, and distributivity. Examples illustrate these concepts, including multiplication techniques and powers. The lecture also explores subtraction, division, and the properties of powers, emphasizing the relationship between products of numbers. Practical applications, such as calculating hours in a year, are used to demonstrate these mathematical principles.